Extraction turbine control system



Jan. 17, 1939.

Inventor: R aym on d Sh ep'p' ard,

IS Attorn ey.

Patented Jan. 11, loss aim maacnon roams common are mmsamnmn.r.,mmtoGeneralllsetrieOompany,-aetrporatlonof New York Application law '8,1038, Serial No. 206,808 4M (Cl-m) The present invention relates toextraction turbine arrangements, and more speciflcally to the type ofextraction turbines in which the flow of extraction fluid through theextraction conduit is uncontrolled. It has been customary to provide athrottle valve in the extraction conduit to reduce pressure fluctuations.or the extraction fluids discharged therefrom. If such extractionturbine is used in conjunction with a system subject to considerableload fluctuations. that is, changes in demand for mechanical load outputfrom the turbine, as is often the case when the turbine is arranged todrive a generator connected to an electric line, it becomes desirable toreduce the flow of extraction fluid preferably completely to close thethrottle valve in that conduit in response to certain load conditions.

vThe object of my invention is to provide an improved extraction turbinearrangement whereby the throttle valve in the extraction oonduit'isclosed upon a certain increase in demand for mechanical load output fromthe extraction turbine. With the closing of the extraction throttlevalve all of the elastic fluid is passed from the extraction stagethrough the lower stages and the mechanical load output of the lowerstages is accordingly increased. The closing of the throttle'valve upona certain load increase may be accomplished in various ways, forinstance, in response to a predetermined drop in the frequency of theelectrical output of the generator driven by the turbine or turbinespeed.

For a better understanding of what I believe to be novel and myinvention, attention is di-- rected to the following description and theclaims appended thereto in connection with the accompanying drawing.

The single flgure of the drawing shows an ex traction turbinearrangement embodying my invention.

The arrangement comprises an extraction turbine it connected for drivingan alternating current generator ii, the turbine having an inlet conduiti2 and an extraction conduit II. The flow of elastic fluid through theinlet conduit I! to the turbine is controlled in a known manner by valvemeans, not shown. The extraction conduit," includes a throttle valve itwhich is normally held in an intermediate position to maintainsubstantially constant the pressure in the discharge conduit l receivingfluid from the extraction conduit ii.

In accordance with my invention, means are provided for automaticallyclosing the throttle valve 14 upon the occurrence of costlitions. In thepresent instance the stem of the throttle valve I4 is connected to apiston ll of a hydraulic motor II. The piston is biased down- I wardlyby a compression spring I8. Actuating fluid under pressure is suppliedto the lower part 5 of the hydraulic motor cylinder by means of a pilotvalve II which has an inlet port 20 and a discharge port 2|. The flow ofactuating fluid through these ports is controlled by a pilot valve head22 providedon the stem 23. In the position indicated, actuating fluidmay be supplied through the inlet port II of the pilot valve to thehydraulic motor ll. when the pilot valve head 22 is moved downward touncover the discharge port II and to cover the inlet port 20, actuatingfluid is discharged from the hydraulic motor I! through the dischargeport ll of the pilot valve. Communication between the discharge port IIand the hydraulic cylinder is established by means including a by-pass24 within the pilot valve cylinder.

The valve head 22 of the pilot valve I9 is adapted to be adjusted inaccordance with predetermined conditions of the load connected to theturbine. As indicated in the drawing, the 25 generator ii may beconnected to any suitable load 2| through conductors 2'. As is wellknown in the art, an abnormal increase of the load tends to reduce thefrequency of the alternating current energy supplied thereto, hence thefrequency of 80 the supply may be used as an indication of the load. Acontact making frequency meter 21, connected across the conductors 28 byleads 28, is arranged for completing an operating circuit 29 upon apredetermined decrease in frequency indi- 85 cation. The circuit 29connected to a suitable source of supply 3| includes an energizing coil3| of an electro-magnetic operator 3!. Upon the energization of thesolenoid Si in response to a predetermined drop in frequency of thegenerstar output, the armature 33 pivotally mounted upon one leg of thecore structure 34 will be lifted causing a downward movement of thearmature extension loosely connected to the pilot valve stem 23. Thus,upon a predetermined drop in frequency of the generator output, thepilot valve head 22 will be moved downwardly to effect the closing ofthe throttle valve it. As the speed of the turbine I0 is subsequentlyincreased to normal and the output frequency of the genso erator ilrestored to its normal condition, the electro-magnetic operator 3! isdeenergized and due to the biasing force of the spring ll provided inthe lower end of the cylinder of the pilot valve ",thevalveheadflwiilberaised toitsnrevious l6 position. Actuating fluid will besupplied to the operating motor I l and the throttle valve in theextraction conduit will be reopened to allow elastic fluid to besupplied to the conduit II.

If the load, 25 connected to the generator II is suddenly reduced,orthrown off, it becomes desirable to close the throttle valve in theextraction conduit because the pressure in the extraction stage undersuch condition is considerably reduced which would permit back flow offluid in the extraction conduit ll. This is accomplished by theprovision of a safety governor- 31 which is driven from the turbineshaft and pivotally connected to the right end of a lever II which hasan intermediate point held on a fulcrum 38 and a left-hand end 40 incooperative relation with a latch ll. The latch 4| normally engages aplate 42 secured to the lower end of a spring 43 and holds such springin a compressed condition. The spring plate 42 is arranged in proximityto the upper end of the pilot valve stem 23.

During operation a sudden increase in speed causes, through the speedgovernor, clockwise rotation of the lever 38 about the fulcrum 39whereby the left end III of the lever is forced upwardly. As the speedreaches a certain maximum value, the left end engages the latch 4| andremoves it from the spring plate 42. The plate is accordingly forceddownwardly into engagement with the pilot valve stem 23 and causesreversing of the pilot valve position resulting in closing movement ofthe throttle valve l4.

Having described the method of operation of my invention together withthe apparatus which I now consider to represent the best embodimentthereof, I desire to have it understood that the apparatus shown is onlyillustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In combination, an extraction turbine, an alternating currentgenerator driven thereby, an extraction conduit extending from saidturbine, a throttle valve in said extraction conduit, means for normallymaintaining said throttle valve in a fixed position and means forautomatically closing said throttle valve upon a predeterminedincreaseinspeedandasthe alternatingcurrent frequency of said electricalgenerator decreases beyond a predetermined minimum value.

2. In combination, an alternating current generator, an elastic fluidturbine for driving said generator, an extraction conduit extending fromsaid turbine, a throttle valve in said extraction conduit, means fornormally holding said throttle valve in a predetermined opened'positionand means for actuating said throttle valve toward a closed positionupon a predetermined decrease in the frequency of the output of saidalternating current generator.

3. In combination, an alternating current generator for supplying avariable load, a turbine for driving said generator, a conduit forextracting elastic fluid from an intermediate stage of said turbine, athrottle valve in said conduit, means for normally maintaining saidthrottle valve in an opened position, means for automatically closingsaid throttle valve upon a predetermined increase in speed of saidturbine, a contact-making means responsive to the frequency of thealternating current output of said generator, and electromagneticactuating means adapted to be energized by said contact-making meansupon a predetermined decrease in the frequency of said generator output,said actuating means being operatively connected for closing saidthrottle valve upon the energization thereof.

4. In combination, an alternating current generator for supplying avariable load, an elastic fluid turbine for driving said generator, anextraction conduit extending from said turbine, a throttle valve in saidconduit, means for normally maintaining said throttle valve in apredetermined opened position, means for closing said throttle valveupon a predetermined increase in speed of said turbine, means responsiveto .a predetermined decrease in the frequency of said generator outputfor closing said throttle valve.

and means for restoring said throttle valve to the opened position uponthe normal frequency of said generator output obtaining.

RAYMOND SHEPPARD.

